• 한국세라믹학회지
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• 제22권5호
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• pp.71-75
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• 1985

This study deals with sintering and corrosive behavior of sintered zircons mixed with 5wt% of clay $Cr_2O_3$ $CrO_3-MgO$ aqueous solution and $CrO_3-Mg(OH)_2$ aqueous solution. Measurements were conducted by firing specimens at 135$0^{\circ}C$ 145$0^{\circ}C$ and 155$0^{\circ}C$ 1$650^{\circ}C$ for 3hrs in oxidized and reduced atmospheric conditions. Following results were obtained. 1. Sintered zircon with 5 wt% clay showed that highest compressive strength and the lowest apparent porosity and the other showed less positive result than above specimen in order of zircon with $CrO_3-MgO$ aqueous solution $CrO_3-Mg(OH)_2$ aqueous solution and $Cr_2O_3$. 2. The more firing temperature increased the more its strength improved and porosity decreased and specimen which was fired over 155$0^{\circ}C$ and in reduced atmospheric condition showed better results. 3. Zircon with additives which was fired over 155$0^{\circ}C$ showed the evidence of thermal dissociation but it was not rebonded completely during cooling. 4. Zircon with $CrO_3-MgO$ aqueous solution and $CrO_3-Mg(OH)_2$ aqueous solutiion showed more corrosive resistance than zircon itself and zircon-clay system.

• Architectural research
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• 제18권2호
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• pp.75-82
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• 2016

To secure the anticorrosive performance of structures in the oceanic environment it is necessary to select appropriate finishing materials and thickness of cover. However, airborne chloride deposition varies depending on the collector used, and it is difficult to select appropriate finishing materials. For this reason, an eight-directional collector is proposed in this study through reviewing the differences between existing airborne chloride collectors and the new one. To analyze airborne chloride deposition according to the direction from which it flows and verify the performance of the collector proposed in this study, airborne chlorides were deposited on the collector for one year at five different locations in an oceanic environment. From the experiment, it was verified that in terms of direction, there were differences in airborne chloride deposition of up to more than 1.5 times. Based on these research findings, the anti-corrosive method applied can be different for each side of a building's structure, and this is believed to serve as an effective and systemic chloride resistance design.

• Environmental Engineering Research
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• 제17권1호
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• pp.17-25
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• 2012

Concern about green water problem has surfaced as a serious issue in Korea. In order to solve this problem, it is necessary to research inhibition of green water and corrosion control of copper pipe in water service. This paper discovered that moderate corrosion inhibitors can solve the green water problem and copper corrosion in water service by adding the optimal concentration of corrosion inhibitors based on regulation. Firstly, in the case of phosphate based corrosion inhibitors, as dosage of the corrosion inhibitor increases from 1 mg/L to 5 mg/L, the relative effect of corrosion inhibitor declines rapidly. Secondly, except for 1 mg/L dosage of silicate based inhibitor, relative effects of the inhibitor displays a positive number depending on inhibitor concentration. The most significant result is that the amount of copper release shows a downward trend, whereas the phosphate based inhibitor accelerates copper ion release as the inhibitor dosage increases. Thirdly, as the dosage of mixed inhibitors increases to 10 mg/L, the copper release change shows a similar trend of phosphate based inhibitor. Lastly, according to the Langelier saturation index (LI), silicate based inhibitors have the most non corrosive value. Larson ratio (LR) indicates that phosphate based inhibitors are the least corrosive. Korea water index (KWI) represents that silicate based inhibitors are most effective in controlling copper pipe corrosion.

• Journal of Welding and Joining
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• 제17권4호
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• pp.53-59
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• 1999

Amorphous alloys have also been called glassy alloys or non-crystalline alloys. They are made by the rapid solidification. The solidification occurs so rapid that the atoms are frozen in their liquid configuration. There are unique magnetic, mechanical, electrical and corrosive behaviors which result form their amorphous structure. In the study. amorphous coatings were manufactured with Ni-Cr-B-Si powders by flame spray. Measurement of hardness, were resistance, corrosion resistance and observation of microstructures and XRD, DSC were performed to investigate characteristics of amorphous coatings. The experimental results obtained as follow: 1) Amorphous powders could not be manufactured with the spraying in the spraying in the liquid nitrogen. But, amorphous coatings could be manufactured with the rotation cooling method by liquid nitrogen. In the fabrication of amorphous coatings, major factor was the rapid cooling by rotation of the substrate. 2) Hardness of coatings was obtained Hv 960 by formation of amorphous phase. But, wear resistance decreased. That was due to porosity in the coatings by the rapid cooling. 3) In the case of corrosion resistance, amorphous coatings were superior to air-cooled coatings. That was due to formation of amorphous phase. 4) After amorphous coatings were heat-treated at 520℃ for 1hr. hardness increased 80% and wear resistance increased 30% comparing with air cooled coatings. These were due to crystallization of amorphous phase and decrease of porosity by heat-treatment.

• Corrosion Science and Technology
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• 제17권4호
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• pp.147-153
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• 2018

Copper is used in various applications in environments favoring and enabling formation of biofilms by naturally occurring microbes. Copper is also the chosen corrosion barrier for nuclear waste in Finland. The copper canisters should have lifetimes of 100,000 years. Copper is commonly considered to be resistant to corrosion in oxygen-free water. This is an important argument for using copper as a corrosion protection in the planned canisters for spent nuclear-fuel encapsulation. However, microbial biofilm formation on metal surfaces can increase corrosion in various conditions and provide conditions where corrosion would not otherwise occur. Microbes can alter pH and redox potential, excrete corrosion-inducing metabolites, directly or indirectly reduce or oxidize the corrosion products, and form biofilms that create corrosive microenvironments. Microbial metabolites are known to initiate, facilitate, or accelerate general or localized corrosion, galvanic corrosion, and intergranular corrosion, as well as enable stress-corrosion cracking. Sulfate-reducing bacteria (SRB) are present in the repository environment. Sulfide is known to be a corrosive agent for copper. Here we show results from corrosion of copper in anoxic simulated ground water in the presence of SRB enriched from the planned disposal site.

• 한국철도학회논문집
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• 제12권5호
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• pp.725-731
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• 2009

강 교량, 선로 구조물, 차량 구조물 등 철도분야에서 강 재료가 많이 사용되고 있다. 설계, 강도평가, 잔존수명 평가 등을 위하여 부식된 강 재료에 대한 인장강도, 피로강도 등이 필요하지만 우리나라의 경우 이 분야의 연구가 미진하여 축적된 데이터가 많지 않다. 본 연구에서는 철도 분야에서 많이 사용되는 대표적인 강 재료에 속하는 SM490A와 SS400에 대해 대기부식 시험절차를 확립하고 많은 시편을 대기부식에 노출시켜 일정한 시간 간격으로 수거하여 인장 및 피로시험을 수행하여 부식시간의 경과에 따른 인장 및 피로강도의 변화를 측정하였다. 처음 3-4개월 기간에 피로강도가 많이 저하하였고 그 이후에는 완만히 변화하였다. 그리고 후열처리 한 시편이 부식에 대한 저항이 더 크다는 것도 알 수 있었다.

• 상하수도학회지
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• 제25권5호
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• pp.707-717
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• 2011

Replacement of old water distribution pipes for protecting water quality induced by pipe corrosion requires enormous budget. Even after the replacement, however, corrosion can occur again at any times and, therefore, inhibitive measure of the corrosion will be not only economical but needed to diminish the consumers' distrust on tap water quality. In 2008, National Environmental Research Institute did a survey on 8 major drinking water source and proposed to establish the Langelier Saturation Index(LI) as a corrosion index in Drinking Water Quality Criteria. Among the water industries of Korea, K-Water is the only one that set up the level of pH over 7.0 and LI above -1.5 on yearly average basis. However, no systematic regulation including LI to inhibit the corrosive tendency has been established yet. In this paper, LI values out of 31 drinking water treatment plants were analyzed and two-stage control of LI value as a measure of corrosive tendency of water is proposed. Primarily, water treatment facilities may operate the system at a target LI value below -1.5. Following the investigation on the effect caused by adjusting the LI value on water quality and corrosiveness, it will be desirable to improve LI value below -1.0 in the long run. In addition to the LI, supplemental use of Larson's modified ratio (LMR) which incorporates hydraulic detention time will be necessary. Several methods to prove the inhibitive effect of improving the LI value on water quality have been also suggested.

• 한국공간구조학회:학술대회논문집
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• 한국공간구조학회 2006년도 춘계 학술발표회 논문집 제3권1호(통권3호)
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• pp.66-72
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• 2006

최근 건축물 및 교량 건설에 있어 연성 재료를 사용함으로써 구조형식의 다양화가 적극적으로 이뤄지고 있는 실정이다. 그 중 하나인 케이블 부재는 인장력의 도입으로 인한 전체 구조물의 강성을 증대시킬 수 있으며 흥미로운 연구 대상이라 할 수 있다. 국내에서도 건축물 또는 교량에 케이블 부재를 사용하는 시공 방법이 점차 증가하고 있고 그에 따라 설계 및 시공 기술도 장족의 발전을 이루고 있다 할 수 있다. 설계에 반영된 케이블 부재가 영구적으로 성능을 유지하기 위해서는 케이블 부재의 방청성능이 가장 중요하나, 이에 대한 기술자들의 인식이 다소 부족한 점을 느껴 본 논문에서 케이블의 방청성능에 대해 고찰 하고자 한다.

• 대한치과의사협회지
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• 제16권2호통권105호
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• pp.107-112
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• 1978

The followings are dealing with 10 dental alloys with less then 30% gold, manufactured by S company 7, and by H company 3. We could find several noticable things by examining them about tarnish and corrosion with human saliva and several other chemicals, and through metal microscopy. 1) After the samples were submerged in human saliva for 3 months, the colour of the samples were no remarkable change. 2) taking a consideration of the error of santorius balance, also there had been little corrosive changes in human saliva. 3) The colour of A-4 was changed into red in 0.05% HCI solution, while that of P-B was changed into black in 0.1% Na₂S solution and severely corroded samples, P-B, X, and Z lost their original colour and turned black. 4) In case of submerging in H₂NO₃reagent, 50%, it caused serious diminishing changes in weight, that is, X 2.7%, Pb 31.0%, Z 40.5%, and there happened tremble corrosive reaction. 5) Seeing them through metal microscopy, we can obserre the corroded samples changed into the shape of.

• 한국건축시공학회지
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• 제3권4호
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• pp.103-109
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• 2003

Reinforced concrete structures under sever conditions such as marine structures, bridges and structural constructed with aggregated(dredged front sea). can be deteriorated from corrosion of the reinforcing bars. The purpose of this study is to evaluate the corrosion reflectance of coated steel using polymer dispersion and polymer cement slurry. Polymer dispersion and polymer cement slurry with various polymer types were coated to the surface of bars and steel plate, and tested for accelerated corrosion tests. Tests include adhesion in tension, bending test, chloride ion spray, penetration of NaCl 10％ solution and carbonation. From the test results, the corrosive resistance of steel is considerably improved by using polymer dispersion and polymer cement flurry at surface of steel. The difference of the corrosive resistance is hardly recognized according to types of polymer dispersion. The coated steel using polymer dispersion and polymer foment slurry will be improved to a great extent compared to those of plain steel when increasing content of chloride ion in cement concrete.